[Qt-interest] Qt/X11 Text Handling on MacOSX faster than Qt/Mac

from
[Josh]

Subject:

[Qt-interest] Qt/X11 Text Handling on MacOSX faster than Qt/Mac

From:

Josh

Date:

Mon, 21 Jun 2010 19:57:26 -0700 PDT

So...
I spent the day fiddling with OSX and was able to get Qt/X11 to run using Fink.
Running my program under Qt/X11 on OSX was probably about 5 times faster than
under Qt/Mac (maybe more, I didn't run official speed tests yet, but it wasn't
even close). As I said, my program is all about text layout/rendering. I'm
pretty sure that this is almost completely due to Harfbuzz being faster than
Core Text, but there could be other factors.
So I'd love someone who is more experienced than I to chime in about the
possibility of getting Harfbuzz to run on Qt/Mac. It seems like if my program
is any sort of indicator, this would be very nice to have as a configure switch
for people who want to get a lot more speed out of the Mac text handling.
Any Trolls to chime in? Is this doable?
Thanks!
Josh
> Thanks for this info, very helpful. Interesting about Core Text being more
> capable than Harfbuzz. When I opened my program I immediately saw some
> (minor) OpenType issues that were not present in Linux/Windows. But I'm
> working with Hebrew, so it might just be in that area. Anyway, I could
> always try to get Qt/X11 working on Mac, I know others have done so, and
> that would give me Harfbuzz, but if anyone has ideas about how to get
> Harfbuzz working on Qt/Mac, let me know. Thanks!
>
> Josh
>
>>> 1) Can someone confirm that Qt is still using ATSUI for Mac?
>>>
>>> 2) Is there any plans to move to Core Text or even Harfbuzz on Mac?
>>
>> Qt will use Core Text when built against Cocoa. This is the default for
>> 64-bit builds, but I believe 32-bit builds will still use Carbon/ATSUI
>> etc by default. We're using the Cocoa build on both 32 and 64-bit and
>> it's working well.
>>
>>> 3) Is there any reason I couldn't make a couple minor changes to the
>> Qt
>>> code and use Harfbuzz on Mac (I don't need any system fonts, I supply
>> all
>>> my own which are all TrueType/OpenType).
>>
>> I've not investigated this, though the idea is interesting. In my
>> experience so far, the Core Text engine is rather more capable than the
>> Harfbuzz implementation on Windows. For example the latter doesn't
>> correctly kern OpenType fonts using the GPOS table (see QTBUG-11389).
>>
>> James
>>
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